Abstract

Powdered shoot extract of Launaea procumbens, a tropical ruderal and agrestal weed, inhibited egg hatch and caused mortality of Meloidogyne javanica juveniles in vitro. However, ethanol extract of L. procumbens did not inhibit radial growth of root-infecting fungi including Macrophomina phaseolina, Fusarium solani and Rhizoctonia solani in vitro. Soil amendment with powdered shoot of L. procumbens markedly reduced root-knot infection caused by M. javanica in mungbean. Population densities of M. javanica were significantly lower in soil amended with 5.0% L. procumbens while a 2.5% amendment did not produce significant reduction in the nematode populations in soil. Whereas low dosage (2.5%) of L. procumbens significantly enhanced plant growth, high dosage (5%) reduced fresh shoot and root weights of mungbean indicating allelopathic effect. Soil amendment with L. procumbens resulted in marked changes in fungal community structure and composition. Fungi like Fusarium semitectum and a sterile fungus (red pigmented) were exclusively isolated from L. procumbens amended soils. On the other hand, all the fungal species isolated from L. procumbens amended soils were also present in unamended soils. Soil amendments with L. procumbens also altered fungal community structure in the root tissues of mungbean. Both general diversity and equitability of fungal community at 2.5% L. procumbens increased appreciably over the controls but at 5% dosage substantially decreased compared to controls, substantially though species richness declined at both the dosages. Dominance concentration followed an opposite trend to that of general diversity.